ReqMulti

ReqMulti is a plugin for the Req HTTP client library in Elixir. It sends multipart/form-data request bodies, built with the multipart library.

Installation

Add req_multi to your list of dependencies in mix.exs:

def deps do
  [
    {:req_multi, "~> 0.1.1"}
  ]
end

Usage

Build a Multipart struct, attach the plugin with ReqMulti.attach/1, and pass the struct through the :multi option:

multipart =
  Multipart.new()
  |> Multipart.add_part(Multipart.Part.text_field("hello world", "greeting"))
  |> Multipart.add_part(Multipart.Part.file_field("/path/to/photo.png", "photo"))

Req.new()
|> ReqMulti.attach()
|> Req.post!(multi: multipart)

The plugin sets the Content-Type (including the multipart boundary) and Content-Length headers and streams the encoded body. Without the :multi option, the request is sent unchanged.

Building the multipart

The %Multipart{} struct comes from the multipart library. Start with Multipart.new/0 and pipe in one part per field or attachment with Multipart.add_part/2. Each part is built with a helper from Multipart.Part:

multipart =
  Multipart.new()
  # a plain form field
  |> Multipart.add_part(Multipart.Part.text_field("hello world", "greeting"))
  # a file read from disk (filename and content-type are inferred from the path)
  |> Multipart.add_part(Multipart.Part.file_field("/path/to/photo.png", "photo"))
  # a file whose contents you already have in memory
  |> Multipart.add_part(
    Multipart.Part.file_content_field("report.pdf", pdf_binary, "document")
  )

Common Multipart.Part builders:

See the Multipart.Part docs for the full list and for the optional headers/opts arguments (e.g. a custom content type).